Bsa optics sweet 17 riflescopes are calibrated to adjust for elliptic bullet drop at any distance between 100 and 300 yds.It features a zoom ring that has an inner drum with markings, and a fixed inner ring with a window cutout.This scope is waterproof, fog-proof and shock-proof.Adj Size: .25 MOAMagnification: 6-18xObjective: 40mmField Of View: 18.80-6.20 ft @ 100 ydsEye Relief: 4"Tube Diameter: 1"Length: 13.80"Weight: 17.60 ozReticle: 30/30Parallax Adjustment: 10 yds-InfinityParallax Adjustment: 10 yds-InfinityProofs: Waterproof, Fogproof, ShockproofCoating Type: Waterproof, Fogproof, ShockproofOptic Coating: Fully Multi-CoatedOptic Coating: Multi-Coated